The latest edition of the Collins English Dictionary published today contains hundreds of new words that its editors say give a snapshot of how society is changing.

“Back, sack and crack” ' a beauty parlour waxing procedure made famous by David Beckham ' is officially defined as “(cosmetic depilation of) the back, scrotum and the area between the buttocks”.

“Heteroflexible” is someone who is usually ' but not always ' heterosexual.

“Supersize”, the fast food menu word for big portions, can now be both an adjective and a verb, as in “supersize me”. And to “go commando” means “to wear no underpants”.

The dictionary is filled with new terms referring to what editor-in-chief Jeremy Butterfield called urban tribes, like “chav” and “chavette”, both derogatory British slang for “a young working class person who dresses in casual sports clothes”.